Electrostatic clamps or chucks (ESCs) are often utilized in the semiconductor industry for clamping workpieces or substrates during plasma-based or vacuum-based semiconductor processes such as ion implantation, etching, chemical vapor deposition (CVD), etc. Clamping capabilities of the ESCs, as well as workpiece temperature control, have proven to be quite valuable in processing semiconductor substrates or wafers, such as silicon wafers. A typical ESC, for example, comprises a dielectric layer positioned over a conductive electrode, wherein the semiconductor wafer is placed on a surface of the ESC (e.g., the wafer is placed on a surface of the dielectric layer). During semiconductor processing (e.g., ion implantation), a clamping voltage is typically applied between the wafer and the electrode, wherein the wafer is clamped against the chuck surface by electrostatic forces.
For certain ion implantation processes, cooling the workpiece via a cooling of the ESC is desirable. At colder temperatures, however, condensation can form on the workpiece, or even freezing of atmospheric water on the surface of the workpiece can occur, when the workpiece is transferred from the cold ESC in the process environment (e.g., a vacuum environment) to an external environment (e.g., a higher pressure, temperature, and humidity environment). For example, after an implantation of ions into the workpiece, the workpiece is typically transferred into a load lock chamber, and the load lock chamber is subsequently is vented. When the load lock chamber is opened to remove the workpiece therefrom, the workpiece is typically exposed to ambient atmosphere (e.g., warm, “wet” air at atmospheric pressure), wherein condensation can occur on the workpiece. The condensation can deposit particles on the workpiece, and/or leave residues on the workpiece that can have adverse effects on front side particles (e.g., on active areas), and can lead to defects and production losses.
Heating of the workpiece can be performed in order to attempt to alleviate the adverse effects of condensation; however, such heating often “soaks” the workpiece for a period of time on the ESC in order to reach a predetermined temperature, prior to transferring the wafer. Long soak times conventionally adversely affect workpiece throughput in the ion implantation system.
Therefore, a need exists in the art for an apparatus, system, and method for mitigating condensation on a workpiece while improving workpiece throughput when transferring a cold workpiece between a “dry” or evacuated environment and a “wet” or atmospheric environment.